The present invention relates to an electric terminal and is applicable particularly, but not exclusively, to reed switches and the like.
In FIGS. 1 and 2, there is illustrated a typical example of the conventional reed switch device which generally includes a reed switch 3 having its leads fixed to a pair of terminal plates 1 and 1 by machine screws or soldering, a pair of terminal screws 9 and 9 threadedly engaging with respective terminal plates 1 and 1 for securing stripped end portions or lead portions of two insulated conductors 7 and 7 with washers 5, and a casing 10, made of an electrically insulating material such as a synthetic resin, glass, etc., for covering the above-mentioned members. In many cases, the threaded shank of terminal screw 9 is inserted into casing 10 from the outside, and the head thereof and the connection portion thereof with respect to conductor 7 are, as shown in FIG. 2, exposed to the outside. In connecting conductor 7, the shank of terminal screw 9 is inserted into a lead portion to be connected to that conductor 7, which lead portion is curled like a ring as shown in FIG. 1, and is then rotated to secure that lead portion. However, if the curled lead portion of conductor 7 is secured by screw 9 with the curling direction of that lead portion being set in the loosening direction of screw 9, the original shape of the lead portion is deformed by the friction with washers 5 and 5 when screw 9 is tightened, so that the securing of the conductor end becomes less positive. This is because the frictional force generated on the deformed lead portion of the conductor becomes smaller due to a smaller stress produced in it by the tightening of terminal screw 9, and because when the lead portion of conductor 7 consists of twisted wires, the wires are untwisted by the rotation of screw 9. It is therefore laborious and time consuming to positively connect the conductor 7.
In order to remove such drawbacks there has been adopted a method in which a terminal lug having an eye is soldered to the lead portion of a conductor, and is then fastened to an electric terminal by inserting terminal screw 9 into the eye thereof and by tightening that screw. However it is also time consuming to solder the terminal lug to the conductor. Alternatively, washer 5 may be provided at its face with a substantially ring-shaped recess, into which the lead portion of a conductor is fitted for the securing thereof. This washer however places limits on the available diameter of the conductor. Furthermore, the connected portions of conductors 7 are exposed to the outside and therefore insulating means are required for insulatedly covering such connection portions when high voltage is applied to the electric terminals. From these reasons there exists a strong need for an electrical terminal which fastens a conductor more easily and positively in a more safe manner.